March 8, 1906] 



NA TURE 



449 



THE VERTICAL DISTRIBUTION OF THE 

 METEOROLOGICAL ELEMENTS ABOVE 

 THE ATLANTIC. 



T N a previous article (vol. lxxiii. pp. 54-56) we described 

 . our expedition to the tropics, and gave the results of 

 the observations with balloons and on mountains, so far 

 as they related to the movements of the upper currents. 

 In the present article we will consider the observations 

 with kites, which furnished nearly continuous records 

 of temperature, humidity, and wind velocity from sea-level 

 to a height of 2300 metres, and the direct observations to 

 a greater height which Mr. Clayton obtained in ascending 

 and descending the tropical peaks on the islands of 

 Teneriffe and Fogo. During a voyage of the White Star 

 steamer Romanic, from Boston to Gibraltar, Mr. Clayton 

 executed six kite-flights, and on board the steam-yacht 

 Otaria, between latitudes 37° and 10° N., longitudes 16 

 and 31° W., with the assistance of M. Maurice, seventeen 

 kite-flights were made, besides two in the harbour of 

 Santa Cruz to investigate the sea breeze, and one in lati- 

 tude 43° 43' N., longitude 8° 43' W., for the study of 

 the changes in the free air produced by the total solar 

 eclipse. The observations obtained at the height of 1000 | 

 metres, compared with those at sea-level, are given in 

 Tables i. and ii. The first table contains the observations 

 made in a general east and west direction between longi- 

 tudes 69 and 16° W., latitudes 42° and 33° N. West of 

 the Azores, that is to say, on the westward slope of the 

 permanent area of high pressure, the decrease of tempera- 

 ture with height was slow, there being two cases out of 

 the four in which the temperature increased immediately 



above the ocean, the average decrease in the thousand 

 metres being but o°4i C. On the eastern and southern 

 slopes of the high pressure the temperature decrease 

 approached the adiabatic rate, amounting on the average 

 to o°73 C. per hundred metres. The relative humidity 

 diminished with altitude over the western barometric slope 

 and increased in the observations obtained over the eastern 

 slope, while the wind veered and increased with altitude 

 in the former locality and backed with diminishing velocity 

 in the latter. Fig. 1 shows the typical vertical distribu- 

 tion of the meteorological elements to the westward of 

 the Azores. 



The observations made at the height of 1000 metres 

 and at sea-level in a general north and south direction, 

 between latitudes 35° and 10° N., appear in Table ii. 

 It will be seen that the temperature decrease is most 

 rapid (average o°78 C. per 100 metres) near the 

 northern and southern limits of the north-east trades, and 

 is least rapid within the trade-wind region (average 

 o°-07 C), due to the presence of strata with inverted 

 temperature gradients, of which a typical example, with 

 the corresponding changes of humidity, is shown in Fig. 2. 

 The relative humidity varies inversely with the tempera- 

 ture, being slightly greater at 1000 metres just outside 

 the trade wind, and much less at this height within the 

 trade belt. While the observations of wind do not indicate 

 any marked deviation from the north-easterly direction, 

 there is a considerable decrease in the velocity of the 

 trade with increasing height. 



Mr. Clayton's study of the data collected in the tropics 

 points to the existence of three strata between the sea 

 and 4000 metres, characterised by differences in tempera- 



Table I. — Conditions at sea-level and at 1000 metres over the Atlantic, between Longitudes 69° and 16° West. 



Table II. — Conditions at sea-level and at 1000 metres over the Atlantic, between Latitudes 35° and io° North. 



Peak of Teneriffe. 



NO. 1897, VOL. 73] 



